Multilayered flexible abrasive containing a layer of electroconductive material

Abstract

The accumulation of electrostatic charges in an abrasive article having a flexible backing sheet, a layer of adhesive and abrasive grains embedded in the adhesive is prevented by incorporating an electroconductive metal pigment or ionizable salt in an inner layer of the article and sandwiching this layer between two layers of substantially lower electroconductance so as to insulate the inner layer.

What is claimed is: 
     
       1. A multilayered abrasive article comprising a flexible backing member layer, at least one adhesive layer of synthetic or animal glue on one face of the backing member layer, and abrasive grains embedded in the adhesive layer, the improvement resulting in the reduction of the accumulation during use of electrostatic surface charges comprising (1) the presence of an inner layer in said abrasive article of sufficient electroconductive material selected from the group consisting of metals, metal alloys, metal pigments, metal salts and metal complexes to render said inner layer significantly more conductive to electrostatic charges than said inner layer would be without said electroconductive material, and (2) on each of the two faces of said inner layer an insulating layer of material having significantly lower electroconductivity than said electroconductive material, said two insulating layers being of the same or different material. 
     
     
       2. The improved abrasive article as defined in claim 1 wherein said ashesive layer on one face of said flexible backing member layer also serves as one of said insulating layers, said electroconductive material is impregnated in said flexible backing member layer, and said abrasive article includes a further layer of low electroconductive material on the other face of said backing member layer, said further layer constituting the second of said insulating layers. 
     
     
       3. The improved abrasive article as defined in claim 1 wherein the inner layer containing the electroconductive material is adjacent to said backing member layer, and said backing member layer constitutes one of said insulating layers. 
     
     
       4. The improved abrasive article as defined in claim 3 wherein said electroconductive material is in said adhesive layer, said flexible backing member layer serving as one of said insulating layers, and a second outer layer of adhesive serving as said second insulating layer is present on said first adhesive layer. 
     
     
       5. The improved abrasive article as defined in claim 3 wherein said inner layer containing said electroconductive material is adjacent to the face of said backing member layer opposite said adhesive layer, and said second insulating layer is present as a separate layer on the other side of said inner layer. 
     
     
       6. The improved abrasive article as defined in claim 1 wherein said inner layer and said two insulating layers are present as separate layers over the adhesive layer on the abrasive side of said article. 
     
     
       7. The improved abrasive article as defined in claim 1 wherein said electroconductive material is a metal, or metal pigment. 
     
     
       8. The improved abrasive article as defined in claim 7 wherein said electroconductive material is a metal pigment. 
     
     
       9. The improved abrasive article as defined in claim 1 wherein said electroconductive material is a metal salt. 
     
     
       10. The improved abrasive article as defined in claim 9 wherein said metal salt is a salt of aluminum, iron, nickel, copper, zinc, silver, tin, lead, sodium, potassium or calcium. 
     
     
       11. The improved abrasive article as defined in claim 7 wherein said electroconductive material is a metal. 
     
     
       12. The improved abrasive article as defined in claim 11 wherein said metal is aluminum, iron, nickel, copper, zinc, silver, tin or lead. 
     
     
       13. The improved abrasive article as defined in claim 1 wherein the resistance of said inner layer is less than 1 megohm and the resistances of said insulating layers are each greater than 1 megohm. 
     
     
       14. The improved abrasive article as defined in claim 13 wherein the resistance of said inner layer is less than about 1 × 10 -   2  megohms and the resistance of said insulating layer is greater than 1 × 10 3  megohms.